Weather radar systems for aircraft typically display radar echoes on a cathode ray tube (CRT) located on an operator's control panel. The weather image is represented in a plan view as the radar antenna sweeps back and forth horizontally. Precipitation intensity is indicated by the color of the radar echoes displayed. The effectiveness of such weather radar systems is limited by the interpretive skill of the operator.
Most systems have the capability to change the position of the radar antenna so that it points up or down. This tilt angle manipulation provides the operator with different views along different horizontal planes through the weather system ahead. Only one horizontal plane or view is displayed at any one time and it is important for the operator to select the correct tilt angle to get an accurate picture of the weather system. For example, the tilt angle of the radar search beam with respect to the aircraft must be such that it intersects the storm below the freezing level since frozen precipitation is a poor reflector of radar energy, while water is a good reflector. If the beam intersects above the freezing level, the storm will be displayed as less severe than it actually is. Thus, some level of conscious effort is required to manipulate the tilt control and interpret the display.
To get a better image of the weather system, or at least to obtain more information about it, operators typically will stop the horizontal scan of the radar antenna and will use the tilt control to scan vertically up and down. Although this provides a vertical image of the storm it does so at only one azimuth angle. U.S. Pat. No. 4,940,987 combines the horizontal scan and vertical scan on the control panel display so that an operator can view both images simultaneously. However, only one horizontal scan or "slice" of the weather system is displayed at one time and only one vertical slice is displayed at one time. Thus, the operator never gets a complete picture. The effectiveness of the system still depends on the operator's skill in selecting the appropriate tilt angle or azimuth angle and/or being able to recall previous images of other slices of the weather system image.
In addition, pilots often need information about weather that is beyond the range of their onboard radar. Currently the pilot must call a flight service station for a verbal report of enroute weather. This verbal communication could be unreliable because of the chance that the weather reporter can be misunderstood. The present invention serves to overcome such difficulty of weather interpretation by presenting the pilot with an accurate display of weather information obtained from independent remotely-located radar station which may be located beyond the range of the pilot's onboard radar.